The present invention relates to a method and system for converting analog signals to digital data.
The method and system for converting analog signals to digital data according to the present invention are useful for, for example, a digital storage oscilloscope.
Since a system for converting analog signals to digital data may be called a digitizer, a system for converting analog signals to digital data will be called a digitizer hereinafter.
FIG. 11 is a drawing showing a conventional digitizer. In FIG. 11, a reference numeral 1 denotes a first amplifier, 2 a sample-and-hold circuit (hereinafter abbreviated to a S/H circuit), 3 a second amplifier for adjusting a gain and offset voltage, 4 an analog-to-digital converter (hereinafter abbreviated to ADC), 31 a variable resistor for gain adjustment, 32 a variable resistor for offset voltage adjustment, and 8 and 9 ADC reference voltage sources.
When the ambient temperature of the digitizer circuit, for example, in FIG. 11 changes, a gain or an offset voltage in the S/H circuit or the amplifier mounted prior to the ADC changes. Conventionally, a change of the amplifier gain or the offset voltage is manually corrected by detecting an output signal from the amplifier with a probe and observing it on a screen of a cathode-ray tube of an oscilloscope, or by referring to a waveform of an output result of the ADC which is reconverted to an analog signal.
For correction of a change of the amplifier gain or the offset voltage by the above conventional digitizes when the ambient temperature of the digitizer circuit is changed, it is extremely difficult to adjust the gain or the offset voltage individually when a plurality of digitizer circuits are connected in parallel to match gains or offset voltages of all signals with each other. In consideration of manufacture, there are some problems imposed by this correction.